This invention relates to a system for automated assembly of electronic components to substrates, such as printed circuit boards, and more particularly relates to systems having multiple assembly stations.
Systems have been in use in the past for programmable, automated assembly of electronic components to substrates. Commonly, automated programmable machines for effecting such assembly are referred to as xe2x80x9cPick and Placexe2x80x9d machines. Such substrates include, but are not limited to, rigid substrates such as printed circuit boards (PCBs) or the like. Unless indicated otherwise, the term xe2x80x9cPCBxe2x80x9d will be used hereinafter to refer not only to conventional printed circuit boards, but also inclusive of all other substrates that may be used with Pick and Place machines, including for example, flex cables. Such electronic components to be assembled to the substrates may include microprocessors, integrated circuits, transistors, resistors, connectors or the like.
Frequently, it is necessary to operatively connect multiple Pick and Place machines in series that form a xe2x80x9clinexe2x80x9d to achieve desired levels of productivity and throughput, or accommodate highly complex PCBs or PCBs with larger numbers of components to be placed. In such a case, certain of the Pick and Place machines in a line will be dedicated to placing certain of the components on the PCB. If one of the Pick and Place machines in the line is inoperative for any reason, it generally is possible for PCBs to be passed through the inoperative machine to other operative machines in the line.
For instance, the HS50 and S23 brand Pick and Place machines from Siemens GmbH of Munich, Germany includes a vertical elevator at each end of a Pick and Place machine with a conveyor extending beneath the machine from the front vertical elevator to the back vertical elevator. In this manner, a particular PCB could bypass the machine by just being conveyed therethrough; such as if the PCB is defective or the machine is inoperative. Alternatively, PCBs could bypass the particular machine by using the vertical elevators and the conveyor underneath the machine if the machine itself is inoperative. However, this approach is relatively slow and cumbersome and not adapted to frequent use in high volume production lines. Moreover, even with such a bypass mechanism, it may be difficult to complete the assembly of all of the components to a particular PCB in one pass. The overall productivity of the serial Pick and Place machines is thus reduced or limited.
In an effort to enhance the productivity of Pick and Place machines, and to conserve on floor space, Pick and Place machines have been produced that include two parallel internal conveyors and two independent Pick and Place mechanism for simultaneously processing two PCBs in parallel on each of the conveyors within a particular machine. Generally, the output from each independent Pick and Place mechanism within a machine is then transported by a separate conveyor to the next machine in the line. However, even with this arrangement, if one of the Pick and Place machines in a line is inoperative, the effectiveness of the entire line is severely impacted.
Therefore, conventional systems for assembling electronic components to printed circuit boards, while having their own utility, may not be entirely satisfactory in terms of redundancy and flexibility, if one or more of the electronic assembly module are inoperative.
The system of the present invention provides a two part of assembly modules for assembling electronic components to a series of printed circuit boards or like PCBs. The pairs of assembly modules are operatively connected in series, and each module includes a pair of assembly stations operating in parallel within the module. Means are provided to bypass the first assembly module and deliver unpopulated PCBs to the second module for processing, while simultaneously bypassing the second assembly module with PCBs populated by the first assembly module. In the event that one of the assembly stations of either assembly module is inoperative, it may be bypassed and the assembly of its electronic components redistributed to the remaining, operative assembly stations to optimize the productivity of the system.
More specifically, the present invention provides a system for populating electronic components onto a plurality of printed circuit boards. The system includes a first assembly module having parallel assembly stations for placing electronic components on an unpopulated printed circuit board and a first bypass conveyer extending through the first assembly module intermediate the parallel assembly stations for conveying unpopulated printed circuit boards therethrough. The system further includes a second assembly module having parallel assembly stations for placing electronic components on an unpopulated printed circuit board and a second bypass conveyor extending through the second assembly module intermediate the parallel assembly stations for conveying populated printed circuit boards therethrough.
The system also includes a shuttle for simultaneously conveying a pair of printed circuit boards between the first and the second assembly modules. The shuttle is shiftable between a first position for either receipt of a populated printed circuit board from one of the assembly stations of the first assembly module and an unpopulated printed circuit board the first bypass conveyor, or transfer of an unpopulated printed circuit board from the first bypass conveyor to one of the assembly stations of the second assembly module, and a second position for either receipt of a populated printed circuit board from the other of the assembly stations of the first assembly module and an unpopulated printed circuit board the first bypass conveyor, or transfer of an unpopulated printed circuit board to the other of the assembly stations of the second assembly module and a populated printed circuit board to the second bypass conveyor;
Wherein the shuttle may be sequentially shifted to the first position to accept a populated printed circuit board from one of the assembly stations of the first assembly module and an unpopulated printed circuit board from the first bypass conveyor, to the second position to transfer the populated printed circuit board to the second bypass conveyor and to transfer the unpopulated printed circuit board to one of the assembly stations of the second assembly module, and to accept a populated printed circuit board from the other of the assembly stations of the first assembly module and an unpopulated printed circuit board from the first bypass conveyor, and to the first position to transfer an unpopulated printed circuit board to the other of the assembly stations of the second assembly module and a populated printed circuit board to the second bypass conveyor.
In one preferred embodiment of the present invention, the system further includes control means for bypassing each of the first and the second assembly stations of the first and second assembly modules by shifting unpopulated printed circuit boards to the respective first or second bypass conveyor.